Development of utility infrastructure includes laying of a variety of pipes underground, and sometimes under water, for carrying various products and services through such pipes, to and from the area being developed.
Some such pipes are quite heavy, such as concrete pipes commonly used for carrying e.g. waste water streams, storm sewer water, and the like. Such concrete pipes are sufficiently heavy that the pipes are laid as pipe sections joined to each other, end to end, typically in a trench or other generally confined course along a path.
The path is generally prepared by digging a trench along the desired path, to a desired depth and at a desired slope needed for gravity flow of the water which is to pass through the pipe. The depth and slope of the trench should be sufficiently deep, and at a desired slope along the length of the trench, to receive and support the pipe at the desired pipe depth and pipe slope.
The length of piping is created along the desired path in the trench by successively laying sections of pipe, end to end, in the trench at the desired pipe depth and pipe slope. Typically, the pipe is supported in the trench by gravel or other fill or bedding material which supports the sides of the pipe, and optionally supports the pipe from underneath, between the bottom of the pipe and the bottom of the elevated trench.
If the pipe is to be supported directly by the bottom of the trench, the trench is dug to the depth desired whereby the bottom of the pipe rests on the bottom of the trench when the pipe is at the desired depth and slope, also referred to herein as elevation/grade and slope. If the fill material is to support the pipe above the bottom surface of the trench, the trench is dug sufficiently deep that the bottom of the pipe is above the bottom of the trench when the pipe is at the desired elevation and slope.
Pipe sections are typically brought to the construction site on a truck and are placed along the proposed path to be traversed by the course of the many pipe sections which are used to create the pipe conduit along the desired path. The pipe sections are thus available, along the path of the pipe line, for placement into the trench, and for being joined to each other to create the pipe line, when the trench has been suitably prepared.
In conventional practice of installing e.g. sewer pipe, a pipe section is, suspended by a single cable, from the end of the working arm of a working machine such as a backhoe, a crane, or the like. In order to pick up the pipe, the cable must be wrapped around the middle of the pipe, since the pipe is to be lifted by a single locus along the length of the pipe. If, as commonly happens, the location where the cable is wrapped does not coincide with the center of gravity of the pipe, the pipe will tip when picked up such that the machine operator will have to set the pipe back down. A worker then adjusts the location of the cable, and the machine operator again attempts to lift the pipe. This process of lift pipe, observe for stability of lifting, lower pipe, adjust position of cable, continues until the cable is properly positioned for reasonably stable lifting of the pipe.
When the pipe is thus lifted, the pipe is free to swing left and right, and to rotate about the cable that suspends it from the working arm of the machine. The amount of such swing, if any, depends on the stability of the cable grip and the skill with which the machine operator handles the controls of the machine. Normally, a worker keeps a stabilizing hand on the pipe section as much as possible, and may hand off stabilizing the pipe section to another worker, for example a worker in the trench, as the pipe is moved toward its engagement location in the trench.
Prior to the pipe being set and positioned in the trench, the trench is prepared for the pipe. For example, where the pipe section is to be laid directly on the bottom of the trench, the depth and slope of the trench is first checked. Where the pipe section is to be laid on a bed of fill such as gravel, the gravel is brought in and prepared, and the elevation of the gravel may be checked.
When the pipe section is lowered into the trench, it is placed on the prepared underlying support at or adjacent the engagement location. Any engagement structure on the pipe section, for example a spigot, may be engaged at this stage in order to better ascertain any deviation from the desired elevation and slope of the pipe section at its finished location. All such manipulation of the pipe section in the trench requires the presence of at least one worker in the trench with the pipe section. The worker guides the pipe section into place, guides the pipe section when the pipe section is being lifted, and adds or removes material underlying the pipe section as required.
Sewer pipe can be, for example, required to be, and to remain, within 0.5 inch of the established running line of pipe sections already laid. As in the case of concrete sewer pipe which is up to 8 or more feet long, and can weight 6 tons or more, placing the weight of the pipe on the fill material or on the bottom of the trench can and does settle and compact underlying loose trench material or underlying fill material. The amount of such settling and compaction varies from location to location along the length of the trench, whether the pipe sections are laid on fill material or trench bottom material.
Thus, when the pipe section is set in the trench, the affect of the weight of the pipe on the settled elevation of the pipe is unknown. Accordingly, it is commonly necessary to lift the pipe section after settling and adjust the fill or trench material to either add material under the pipe section or remove material from under the pipe section. Such lifting, and adding or removal of fill material, requires continued presence of the worker in the trench, with the corresponding cost of such labor, and the risk that the worker may be injured, by the heavy pipe section or the lifting arm of the lifting machine.
After each such addition or removal of material under the pipe section, the pipe section is again set in place and the elevation and grade checked. This process is repeated until the pipe section is settled within specification, on path, at grade, and on slope.
Where the pipe is being laid under water, the difficulty and complexity of the process is further compounded by workers in the trench having to contend with the water. In some cases, the water is simply a nuisance. In other cases, the worker must put his head under water in order to check on the condition, placement, or other positioning of the pipe section. In addition, the worker may have to keep his head under water and give the machine operator hand signals to enable the machine operator to maneuver the pipe section into engagement with the previously laid section of pipe. Where the water is deeper, the worker in the trench may have to be completely submerged while checking the pipe section, whereby the work is even further delayed while the diver submerges and subsequently surfaces to communicate the results of this under water inspection.
An additional problem with such process is the low productivity associated with such trial and error placement of the respective pipe sections.
Thus, it is an object of the invention to provide improved apparatus and methods for laying a series of pipe sections, or other elongate workpieces, engaged in end to end relationship along a path to be traversed by such pipe sections, or other elongate workpieces.
It is another object to provide instrumentation and control of such process such that the pipe section is placed at grade, on line, and on slope the first time the pipe section is laid in the trench and engaged with the previously laid pipe section.
It is yet another object to provide apparatus and methods for laying and engaging such pipe section whereby no worker is needed in the trench for routine placement and engaging of such pipe sections.
It is still another object to provide apparatus and methods whereby the fill or bedding material is placed and settled about the pipe section while the pipe section is being held at the specified grade and slope, and in the specified direction.
Still another object is to provide apparatus and methods whereby the pipe section is held suspended above any underlying support during engagement of the pipe section with the previously laid pipe section, and is held in such position while fill or bedding material is placed and consolidated about the pipe section.
It is yet another object to provide a working implement which is rigidly mounted to the working arm of a working machine, such as a backhoe or crane, so that the working implement moves together as one with the working arm of the working machine.
It is a further object of the invention to provide a working implement having at least two level sensors providing level indications to control apparatus, the control apparatus sending control signals to activation elements which adjust the slope angle of the centerline or the bottom of a pipe section being gripped by grip elements of the implement.
It is yet another object of the invention to provide a working implement for lifting and placing pipe sections, the implement including vibrators disposed alongside the implement such that the vibrators assist with consolidation of fill material placed beside a pipe section being held in position in the trench, and optionally to employ a slurry of such fill material to assist with such consolidation.
A further object is to provide a working implement for lifting and placing a pipe section, including a cross-slope actuator on the implement affecting displacement of the pipe section in an arcuate direction transverse to the longitudinal centerline of the pipe section.
A further object is to provide an implement having an insertion cylinder that bears the weight of the pipe section being lifted and placed in the trench.
Still another object is to provide a plurality of gripping element arrangements for gripping the pipe sections, including (i) two opposed pairs of gripping arms wherein each gripping arm is articulated, (ii) a pair of pipe stops receiving a pipe section held in place by an articulated arm on the opposing side of the pipe, (iii) downwardly-extending sliding grip arms on opposing sides of the pipe whereby the grip arms move along their respective longitudinal axes to secure a pipe section against an upper stop bracket, and (iv) a lifting pig inserted into an open end of the pipe for lifting of the pipe section.
It is yet another object to sense elevation and alignment of the implement, and slope of the centerline or bottom of a pipe section being held by the grip elements, and to send position and slope commands to suitable actuators on the implement to position the implement, and set the proper slope for engaging a previously laid pipe at the desired grade, alignment, and slope.